In the following reaction sequence, the major product P is formed. (see reaction scheme) Glycerol reacts completely with excess P in the presence of an acid catalyst to form Q. Reaction of Q with excess NaOH followed by the treatment with $\mathrm{CaCl}_{2}$ yields Ca-soap R, quantitatively. Starting with one mole of Q, the amount of R produced in gram is ____. [Given, atomic weight: $\mathrm{H}=1$, $\mathrm{C}=12$, $\mathrm{~N}=14$, $\mathrm{O}=16$, $\mathrm{Na}=23$, $\mathrm{Cl}=35$, $\mathrm{Ca}=40$]

Chemistry in Everyday Life — JEE Advanced · 2024 · 26 May 2024 · Paper 1 Question with Solution

In the following reaction sequence, the major product P is formed.

(see reaction scheme)

Glycerol reacts completely with excess P in the presence of an acid catalyst to form Q. Reaction of Q with excess NaOH followed by the treatment with

CaCl_{2}

yields Ca-soap R, quantitatively.

Starting with one mole of Q, the amount of R produced in gram is ____.
[Given, atomic weight:

H = 1

C = 12

N = 14

O = 16

Na = 23

Cl = 35

Ca = 40

]

Answer: 909

Solution

The scheme furnishes octadecanoic (stearic) acid, a

C_{18}

carboxylic acid, as

P

. Glycerol esterifies with excess

P

to the triester glyceryl tristearate,

Q

. Saponification of one mole of

Q

with sodium hydroxide gives three moles of sodium stearate, and treatment with

CaC l_{2}

converts these to calcium stearate,

(C_{17} H_{35} COO)_{2} Ca

, because two carboxylate groups bind one

C a^{2 +}

. Three moles of the sodium salt therefore give

\frac{3}{2}

mole of calcium stearate, whose molar mass is

2 \times 283 + 40 = 606

. The mass of

R

\frac{3}{2} \times 606 = 909

JEE Advanced · 2024 · 26 May 2024 · Paper 1 · Integer answer

JEE Advanced · 2024 · 26 May 2024 · Paper 1 · Chemistry in Everyday Life

Solution